Canadian football

Three downs, a field that's 10 yards wider and longer, with end zones 10 yards deeper. Evolved from Canadianrugby, with sides of 15 reduced to the current 12 early in the 20th century - the first attempt to Americanize the game. A later Americanization came in the 50s, and was the start of a 20-year period in which leagues on both sides of the border competed to sign top US talent. As the NFL and AFL boomed, thanks to the infusion of Big TV money that began in the 60s, the parity was lost.